Tablets for pharmaceutical, confectionery or food applications are mostly made with starch or sugar as excipients. The use of white starch for making tablets has been described in European patent EP 0 564 700.
Generally, starch products are relatively easy to compress and they give a tablet, which is easily soluble and has the required hardness. The tablet, which may contain as an active ingredient a pharmaceutical product, should readily disintegrate in water and in the gastrointestinal tract after being swallowed.
The tablet does not only contain the drug or a reagent, it also contains other ingredients which act as fillers, such as lactose or phosphates; lubricating agents, such as talc, stearic acid or paraffin and disintegrating agents, such as carboxymethyl-cellulose or starch. For confectionery purposes the tablets often include aroma's and colorants at low concentration.
With the present interest in the use of sugar-free and/or low calorie products, the use of starch-based and sugar excipients is seriously questioned. Sugar alcohols, such as xylitol, maltitol, sorbitol, mannitol and erythritol are already widely used for sugar replacement. Sugar alcohols have a much lower caloric content than sugar. The use of several sugar alcohols as excipients was extensively tested. Until now it has not been possible to use erythritol as a suitable excipient because compression resulted in a product which was much too brittle.
Direct compression of spray-dried erythritol has been described in European patent EP 0 497 439. The hardness of the product was found to be too low for normal application.
U.S. Pat. No. 3,341,415 by Scott, describes a process for preparing mannitol-based excipients. The process comprises the mixing of mannitol with a second sugar, heating the mixture and preferably congealing the mixture. The product is then used for tabletting. The mixture based on mannitol and erythritol gives rise to a tablet with a friability which is too high and a tensile strength which is too low for good application in tablets as illustrated by the examples of the invention which forms the subject of the present patent application.
U.S. Pat. No. 3,639,168 by Monti et al. describes the preparation of a direct compression vehicle by dispersing a diluant such as sugar, in a fully hydrated hydratable polymer, such as starch, drying the resulting dispersion, and reducing the dried product to particles of the desired size.
European patent application EP 0 528 604 discloses the co-crystallized sorbitol and xylitol and tablets made therefrom.
European patent application EP 0 509 606 relates to the production of tabletting excipients containing lactose, having a high .beta.-lactose content.
Recently, it was described that erythritol is not only non-cariogenic but that it also has an anti-cariogenic activity. When starch, which is normally cariogenic is mixed with a sufficient amount of erythritol the product is non-cariogenic. This finding, which forms the subject of a co-pending patent application, only increases the interest in the use of erythritol as an excipient.